Abstract: A magnetic brush apparatus for use in electrographic copiers and the like for applying magnetic developer to electrostatic images at a development zone to effect development of such images. Such apparatus includes a non-magnetic sleeve having a rotatably driven magnetic roller therein, and magnetic shunt means for selectively reducing the magnetic field produced by the magnetic roller outside the sleeve. By reducing the magnetic field shortly after the developer first contacts the image and maintaining the reduced field until the developed image is advanced beyond the influence of the magnetic roller, a trailing edge development artifact is avoided.